Smart playlists

Basically directly pulled from http-music. Want to make a nice UI for
this eventually ("opening playlist..." popup dialog), but not for now.

7 files changed, 589 insertions, 1 deletions

diff --git a/crawlers.js b/crawlers.js
new file mode 100644
index 0000000..0bf5c4e
--- /dev/null
+++ b/crawlers.js
@@ -0,0 +1,259 @@
+const fs = require('fs')
+const path = require('path')
+const naturalSort = require('node-natural-sort')
+const fetch = require('node-fetch')
+const cheerio = require('cheerio')
+const url = require('url')
+const { downloadPlaylistFromOptionValue, promisifyProcess } = require('./general-util')
+const { spawn } = require('child_process')
+
+const { promisify } = require('util')
+const readDir = promisify(fs.readdir)
+const stat = promisify(fs.stat)
+
+function sortIgnoreCase(sortFunction) {
+  return function(a, b) {
+    return sortFunction(a.toLowerCase(), b.toLowerCase())
+  }
+}
+
+function crawlHTTP(absURL, opts = {}, internals = {}) {
+  // Recursively crawls a given URL, following every link to a deeper path and
+  // recording all links in a tree (in the same format playlists use). Makes
+  // multiple attempts to download failed paths.
+
+  const {
+    verbose = false,
+
+    maxAttempts = 5,
+
+    keepSeparateHosts = false,
+    stayInSameDirectory = true,
+
+    keepAnyFileType = false,
+    fileTypes = ['wav', 'ogg', 'oga', 'mp3', 'mp4', 'm4a', 'mov', 'mpga', 'mod'],
+
+    filterRegex = null
+  } = opts
+
+  if (!internals.attempts) internals.attempts = 0
+
+  // TODO: Should absURL initially be added into this array? I'd like to
+  // re-program this entire crawl function to make more sense - "internal"
+  // dictionaries aren't quite easy to reason about!
+  if (!internals.allURLs) internals.allURLs = []
+
+  const verboseLog = text => {
+    if (verbose) {
+      console.error(text)
+    }
+  }
+
+  const absURLObj = new url.URL(absURL)
+
+  return fetch(absURL)
+    .then(
+      res => res.text().then(async text => {
+        const links = getHTMLLinks(text)
+
+        const items = []
+
+        for (const link of links) {
+          let [ name, href ] = link
+
+          // If the name (that's the content inside of <a>..</a>) ends with a
+          // slash, that's probably just an artifact of a directory lister;
+          // not actually part of the intended content. So we remove it!
+          if (name.endsWith('/')) {
+            name = name.slice(0, -1)
+          }
+
+          name = name.trim()
+
+          const urlObj = new url.URL(href, absURL + '/')
+          const linkURL = url.format(urlObj)
+
+          if (internals.allURLs.includes(linkURL)) {
+            verboseLog("[Ignored] Already done this URL: " + linkURL)
+            continue
+          }
+
+          internals.allURLs.push(linkURL)
+
+          if (filterRegex && !(filterRegex.test(linkURL))) {
+            verboseLog("[Ignored] Failed regex: " + linkURL)
+            continue
+          }
+
+          if (!keepSeparateHosts && urlObj.host !== absURLObj.host) {
+            verboseLog("[Ignored] Inconsistent host: " + linkURL)
+            continue
+          }
+
+          if (stayInSameDirectory) {
+            const relative = path.relative(absURLObj.pathname, urlObj.pathname)
+            if (relative.startsWith('..') || path.isAbsolute(relative)) {
+              verboseLog("[Ignored] Outside of parent directory: " + linkURL)
+              continue
+            }
+          }
+
+          if (href.endsWith('/')) {
+            // It's a directory!
+
+            verboseLog("[Dir] " + linkURL)
+
+            items.push(await (
+              crawlHTTP(linkURL, opts, Object.assign({}, internals))
+                .then(({ items }) => ({name, items}))
+            ))
+          } else {
+            // It's a file!
+
+            const extensions = fileTypes.map(t => '.' + t)
+
+            if (
+              !keepAnyFileType &&
+              !(extensions.includes(path.extname(href)))
+            ) {
+              verboseLog("[Ignored] Bad extension: " + linkURL)
+              continue
+            }
+
+            verboseLog("[File] " + linkURL)
+            items.push({name, downloaderArg: linkURL})
+          }
+        }
+
+        return {items}
+      }),
+
+      err => {
+        console.warn("Failed to download: " + absURL)
+
+        if (internals.attempts < maxAttempts) {
+          console.warn(
+            `Trying again. Attempt ${internals.attempts + 1}/${maxAttempts}...`
+          )
+
+          return crawlHTTP(absURL, opts, Object.assign({}, internals, {
+            attempts: internals.attempts + 1
+          }))
+        } else {
+          console.error(
+            "We've hit the download attempt limit (" + maxAttempts + "). " +
+            "Giving up on this path."
+          )
+
+          throw 'FAILED_DOWNLOAD'
+        }
+      }
+    )
+    .catch(error => {
+      if (error === 'FAILED_DOWNLOAD') {
+        // Debug logging for this is already handled above.
+        return []
+      } else {
+        throw error
+      }
+    })
+}
+
+function getHTMLLinks(text) {
+  // Never parse HTML with a regex!
+  const $ = cheerio.load(text)
+
+  return $('a').get().map(el => {
+    const $el = $(el)
+    return [$el.text(), $el.attr('href')]
+  })
+}
+
+
+
+function crawlLocal(dirPath, extensions = [
+  'ogg', 'oga',
+  'wav', 'mp3', 'mp4', 'm4a', 'aac',
+  'mod'
+]) {
+  return readDir(dirPath).then(items => {
+    items.sort(sortIgnoreCase(naturalSort()))
+
+    return Promise.all(items.map(item => {
+      const itemPath = path.join(dirPath, item)
+
+      return stat(itemPath).then(stats => {
+        if (stats.isDirectory()) {
+          return crawlLocal(itemPath, extensions)
+            .then(group => Object.assign({name: item}, group))
+        } else if (stats.isFile()) {
+          // Extname returns a string starting with a dot; we don't want the
+          // dot, so we slice it off of the front.
+          const ext = path.extname(item).slice(1)
+
+          if (extensions.includes(ext)) {
+            // The name of the track doesn't include the file extension; a user
+            // probably wouldn't add the file extensions to a hand-written
+            // playlist, or want them in an auto-generated one.
+            const basename = path.basename(item, path.extname(item))
+
+            const track = {name: basename, downloaderArg: itemPath}
+            return track
+          } else {
+            return null
+          }
+        }
+      })
+    }))
+  }).then(items => items.filter(Boolean))
+    .then(filteredItems => ({items: filteredItems}))
+}
+
+async function crawlYouTube(url) {
+  const ytdl = spawn('youtube-dl', [
+    '-j', // Output as JSON
+    '--flat-playlist',
+    url
+  ])
+
+  const items = []
+
+  ytdl.stdout.on('data', data => {
+    const lines = data.toString().trim().split('\n')
+
+    items.push(...lines.map(JSON.parse))
+  })
+
+  // Pass false so it doesn't show logging.
+  await promisifyProcess(ytdl, false)
+
+  return {
+    items: items.map(item => {
+      return {
+        name: item.title,
+        downloaderArg: 'https://youtube.com/watch?v=' + item.id
+      }
+    })
+  }
+}
+
+async function openFile(input) {
+  return JSON.parse(await downloadPlaylistFromOptionValue(input))
+}
+
+module.exports = {
+  crawlHTTP,
+  crawlLocal,
+  crawlYouTube,
+  openFile,
+
+  getCrawlerByName: function(name) {
+    switch (name) {
+      case 'crawl-http': return crawlHTTP
+      case 'crawl-local': return crawlLocal
+      case 'crawl-youtube': return crawlYouTube
+      case 'open-file': return openFile
+      default: return null
+    }
+  }
+}
diff --git a/general-util.js b/general-util.js
index 35e1103..879219d 100644
--- a/general-util.js
+++ b/general-util.js
@@ -46,3 +46,20 @@ module.exports.killProcess = async function(proc) {
     proc.kill()
   }
 }
+
+function downloadPlaylistFromURL(url) {
+  return fetch(url).then(res => res.text())
+}
+
+function downloadPlaylistFromLocalPath(path) {
+  return readFile(path).then(buf => buf.toString())
+}
+
+module.exports.downloadPlaylistFromOptionValue = function(arg) {
+  // TODO: Verify things!
+  if (arg.startsWith('http://') || arg.startsWith('https://')) {
+    return downloadPlaylistFromURL(arg)
+  } else {
+    return downloadPlaylistFromLocalPath(arg)
+  }
+}
diff --git a/index.js b/index.js
index df60207..72c2383 100644
--- a/index.js
+++ b/index.js
@@ -2,6 +2,7 @@
 
 const { AppElement } = require('./ui')
 const { updatePlaylistFormat } = require('./playlist-utils')
+const processSmartPlaylist = require('./smart-playlist')
 const ansi = require('./tui-lib/util/ansi')
 const CommandLineInterfacer = require('./tui-lib/util/CommandLineInterfacer')
 const EventEmitter = require('events')
@@ -65,10 +66,13 @@ async function main() {
   }
 
   if (process.argv[2]) {
+    flushable.write(ansi.moveCursor(0, 0))
+    flushable.write('Opening playlist...')
+    flushable.flush()
     grouplike = require(process.argv[2])
   }
 
-  grouplike = updatePlaylistFormat(grouplike)
+  grouplike = await processSmartPlaylist(grouplike)
 
   appElement.grouplikeListingElement.loadGrouplike(grouplike)
 
diff --git a/package-lock.json b/package-lock.json
index e9fd90f..c0a7cfe 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -4,16 +4,103 @@
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
+    "@types/node": {
+      "version": "10.3.1",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-10.3.1.tgz",
+      "integrity": "sha512-IsX9aDHDzJohkm3VCDB8tkzl5RQ34E/PFA29TQk6uDGb7Oc869ZBtmdKVDBzY3+h9GnXB8ssrRXEPVZrlIOPOw=="
+    },
+    "boolbase": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/boolbase/-/boolbase-1.0.0.tgz",
+      "integrity": "sha1-aN/1++YMUes3cl6p4+0xDcwed24="
+    },
+    "cheerio": {
+      "version": "1.0.0-rc.2",
+      "resolved": "https://registry.npmjs.org/cheerio/-/cheerio-1.0.0-rc.2.tgz",
+      "integrity": "sha1-S59TqBsn5NXawxwP/Qz6A8xoMNs=",
+      "requires": {
+        "css-select": "~1.2.0",
+        "dom-serializer": "~0.1.0",
+        "entities": "~1.1.1",
+        "htmlparser2": "^3.9.1",
+        "lodash": "^4.15.0",
+        "parse5": "^3.0.1"
+      }
+    },
     "command-exists": {
       "version": "1.2.6",
       "resolved": "https://registry.npmjs.org/command-exists/-/command-exists-1.2.6.tgz",
       "integrity": "sha512-Qst/zUUNmS/z3WziPxyqjrcz09pm+2Knbs5mAZL4VAE0sSrNY1/w8+/YxeHcoBTsO6iojA6BW7eFf27Eg2MRuw=="
     },
+    "core-util-is": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/core-util-is/-/core-util-is-1.0.2.tgz",
+      "integrity": "sha1-tf1UIgqivFq1eqtxQMlAdUUDwac="
+    },
     "crypto-random-string": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/crypto-random-string/-/crypto-random-string-1.0.0.tgz",
       "integrity": "sha1-ojD2T1aDEOFJgAmUB5DsmVRbyn4="
     },
+    "css-select": {
+      "version": "1.2.0",
+      "resolved": "https://registry.npmjs.org/css-select/-/css-select-1.2.0.tgz",
+      "integrity": "sha1-KzoRBTnFNV8c2NMUYj6HCxIeyFg=",
+      "requires": {
+        "boolbase": "~1.0.0",
+        "css-what": "2.1",
+        "domutils": "1.5.1",
+        "nth-check": "~1.0.1"
+      }
+    },
+    "css-what": {
+      "version": "2.1.0",
+      "resolved": "https://registry.npmjs.org/css-what/-/css-what-2.1.0.tgz",
+      "integrity": "sha1-lGfQMsOM+u+58teVASUwYvh/ob0="
+    },
+    "dom-serializer": {
+      "version": "0.1.0",
+      "resolved": "https://registry.npmjs.org/dom-serializer/-/dom-serializer-0.1.0.tgz",
+      "integrity": "sha1-BzxpdUbOB4DOI75KKOKT5AvDDII=",
+      "requires": {
+        "domelementtype": "~1.1.1",
+        "entities": "~1.1.1"
+      },
+      "dependencies": {
+        "domelementtype": {
+          "version": "1.1.3",
+          "resolved": "https://registry.npmjs.org/domelementtype/-/domelementtype-1.1.3.tgz",
+          "integrity": "sha1-vSh3PiZCiBrsUVRJJCmcXNgiGFs="
+        }
+      }
+    },
+    "domelementtype": {
+      "version": "1.3.0",
+      "resolved": "https://registry.npmjs.org/domelementtype/-/domelementtype-1.3.0.tgz",
+      "integrity": "sha1-sXrtguirWeUt2cGbF1bg/BhyBMI="
+    },
+    "domhandler": {
+      "version": "2.4.2",
+      "resolved": "https://registry.npmjs.org/domhandler/-/domhandler-2.4.2.tgz",
+      "integrity": "sha512-JiK04h0Ht5u/80fdLMCEmV4zkNh2BcoMFBmZ/91WtYZ8qVXSKjiw7fXMgFPnHcSZgOo3XdinHvmnDUeMf5R4wA==",
+      "requires": {
+        "domelementtype": "1"
+      }
+    },
+    "domutils": {
+      "version": "1.5.1",
+      "resolved": "https://registry.npmjs.org/domutils/-/domutils-1.5.1.tgz",
+      "integrity": "sha1-3NhIiib1Y9YQeeSMn3t+Mjc2gs8=",
+      "requires": {
+        "dom-serializer": "0",
+        "domelementtype": "1"
+      }
+    },
+    "entities": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/entities/-/entities-1.1.1.tgz",
+      "integrity": "sha1-blwtClYhtdra7O+AuQ7ftc13cvA="
+    },
     "es6-error": {
       "version": "3.2.0",
       "resolved": "https://registry.npmjs.org/es6-error/-/es6-error-3.2.0.tgz",
@@ -42,11 +129,34 @@
       "resolved": "https://registry.npmjs.org/graceful-fs/-/graceful-fs-4.1.11.tgz",
       "integrity": "sha1-Dovf5NHduIVNZOBOp8AOKgJuVlg="
     },
+    "htmlparser2": {
+      "version": "3.9.2",
+      "resolved": "https://registry.npmjs.org/htmlparser2/-/htmlparser2-3.9.2.tgz",
+      "integrity": "sha1-G9+HrMoPP55T+k/M6w9LTLsAszg=",
+      "requires": {
+        "domelementtype": "^1.3.0",
+        "domhandler": "^2.3.0",
+        "domutils": "^1.5.1",
+        "entities": "^1.1.1",
+        "inherits": "^2.0.1",
+        "readable-stream": "^2.0.2"
+      }
+    },
     "iac": {
       "version": "1.1.0",
       "resolved": "https://registry.npmjs.org/iac/-/iac-1.1.0.tgz",
       "integrity": "sha1-C83Rc3Jy/qwj5126pFeCnYHTtMw="
     },
+    "inherits": {
+      "version": "2.0.3",
+      "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.3.tgz",
+      "integrity": "sha1-Yzwsg+PaQqUC9SRmAiSA9CCCYd4="
+    },
+    "isarray": {
+      "version": "1.0.0",
+      "resolved": "https://registry.npmjs.org/isarray/-/isarray-1.0.0.tgz",
+      "integrity": "sha1-u5NdSFgsuhaMBoNJV6VKPgcSTxE="
+    },
     "js-base64": {
       "version": "2.4.5",
       "resolved": "https://registry.npmjs.org/js-base64/-/js-base64-2.4.5.tgz",
@@ -60,6 +170,11 @@
         "graceful-fs": "^4.1.6"
       }
     },
+    "lodash": {
+      "version": "4.17.10",
+      "resolved": "https://registry.npmjs.org/lodash/-/lodash-4.17.10.tgz",
+      "integrity": "sha512-UejweD1pDoXu+AD825lWwp4ZGtSwgnpZxb3JDViD7StjQz+Nb/6l093lx4OQ0foGWNRoc19mWy7BzL+UAK2iVg=="
+    },
     "minimist": {
       "version": "0.0.8",
       "resolved": "https://registry.npmjs.org/minimist/-/minimist-0.0.8.tgz",
@@ -78,6 +193,51 @@
       "resolved": "https://registry.npmjs.org/node-fetch/-/node-fetch-2.1.2.tgz",
       "integrity": "sha1-q4hOjn5X44qUR1POxwb3iNF2i7U="
     },
+    "node-natural-sort": {
+      "version": "0.8.6",
+      "resolved": "https://registry.npmjs.org/node-natural-sort/-/node-natural-sort-0.8.6.tgz",
+      "integrity": "sha1-AdxrrcR0OxYDNAjw2FiasubAlM8="
+    },
+    "nth-check": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/nth-check/-/nth-check-1.0.1.tgz",
+      "integrity": "sha1-mSms32KPwsQQmN6rgqxYDPFJquQ=",
+      "requires": {
+        "boolbase": "~1.0.0"
+      }
+    },
+    "parse5": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/parse5/-/parse5-3.0.3.tgz",
+      "integrity": "sha512-rgO9Zg5LLLkfJF9E6CCmXlSE4UVceloys8JrFqCcHloC3usd/kJCyPDwH2SOlzix2j3xaP9sUX3e8+kvkuleAA==",
+      "requires": {
+        "@types/node": "*"
+      }
+    },
+    "process-nextick-args": {
+      "version": "2.0.0",
+      "resolved": "https://registry.npmjs.org/process-nextick-args/-/process-nextick-args-2.0.0.tgz",
+      "integrity": "sha512-MtEC1TqN0EU5nephaJ4rAtThHtC86dNN9qCuEhtshvpVBkAW5ZO7BASN9REnF9eoXGcRub+pFuKEpOHE+HbEMw=="
+    },
+    "readable-stream": {
+      "version": "2.3.6",
+      "resolved": "https://registry.npmjs.org/readable-stream/-/readable-stream-2.3.6.tgz",
+      "integrity": "sha512-tQtKA9WIAhBF3+VLAseyMqZeBjW0AHJoxOtYqSUZNJxauErmLbVm2FW1y+J/YA9dUrAC39ITejlZWhVIwawkKw==",
+      "requires": {
+        "core-util-is": "~1.0.0",
+        "inherits": "~2.0.3",
+        "isarray": "~1.0.0",
+        "process-nextick-args": "~2.0.0",
+        "safe-buffer": "~5.1.1",
+        "string_decoder": "~1.1.1",
+        "util-deprecate": "~1.0.1"
+      }
+    },
+    "safe-buffer": {
+      "version": "5.1.2",
+      "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.1.2.tgz",
+      "integrity": "sha512-Gd2UZBJDkXlY7GbJxfsE8/nvKkUEU1G38c1siN6QP6a9PT9MmHB8GnpscSmMJSoF8LOIrt8ud/wPtojys4G6+g=="
+    },
     "sanitize-filename": {
       "version": "1.6.1",
       "resolved": "https://registry.npmjs.org/sanitize-filename/-/sanitize-filename-1.6.1.tgz",
@@ -86,6 +246,14 @@
         "truncate-utf8-bytes": "^1.0.0"
       }
     },
+    "string_decoder": {
+      "version": "1.1.1",
+      "resolved": "https://registry.npmjs.org/string_decoder/-/string_decoder-1.1.1.tgz",
+      "integrity": "sha512-n/ShnvDi6FHbbVfviro+WojiFzv+s8MPMHBczVePfUpDJLwoLT0ht1l4YwBCbi8pJAveEEdnkHyPyTP/mzRfwg==",
+      "requires": {
+        "safe-buffer": "~5.1.0"
+      }
+    },
     "temp-dir": {
       "version": "1.0.0",
       "resolved": "https://registry.npmjs.org/temp-dir/-/temp-dir-1.0.0.tgz",
@@ -125,6 +293,11 @@
       "version": "1.0.4",
       "resolved": "https://registry.npmjs.org/utf8-byte-length/-/utf8-byte-length-1.0.4.tgz",
       "integrity": "sha1-9F8VDExm7uloGGUFq5P8u4rWv2E="
+    },
+    "util-deprecate": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/util-deprecate/-/util-deprecate-1.0.2.tgz",
+      "integrity": "sha1-RQ1Nyfpw3nMnYvvS1KKJgUGaDM8="
     }
   }
 }
diff --git a/package.json b/package.json
index b26650a..e2501ab 100644
--- a/package.json
+++ b/package.json
@@ -9,6 +9,7 @@
   "author": "",
   "license": "GPL-3.0",
   "dependencies": {
+    "cheerio": "^1.0.0-rc.2",
     "command-exists": "^1.2.6",
     "fifo-js": "^2.1.0",
     "fs-extra": "^6.0.1",
@@ -16,6 +17,7 @@
     "js-base64": "^2.4.5",
     "mkdirp": "^0.5.1",
     "node-fetch": "^2.1.2",
+    "node-natural-sort": "^0.8.6",
     "sanitize-filename": "^1.6.1",
     "tempy": "^0.2.1"
   }
diff --git a/smart-playlist.js b/smart-playlist.js
new file mode 100644
index 0000000..09badd9
--- /dev/null
+++ b/smart-playlist.js
@@ -0,0 +1,131 @@
+const { getCrawlerByName } = require('./crawlers')
+const { isGroup, filterTracks, sourceSymbol, updatePlaylistFormat } = require('./playlist-utils')
+
+async function processSmartPlaylist(item, topItem = true) {
+  // Object.assign is used so that we keep original properties, e.g. "name"
+  // or "apply". (It's also used so we return copies of original objects.)
+
+  if (topItem) {
+    item = await updatePlaylistFormat(item)
+  }
+
+  const newItem = Object.assign({}, item)
+
+  if ('source' in newItem) {
+    const [ name, ...args ] = item.source
+
+    const crawl = getCrawlerByName(name)
+
+    if (crawl) {
+      Object.assign(newItem, await crawl(...args))
+    } else {
+      console.error(`No crawler by name ${name} - skipped item:`, item)
+      newItem.failed = true
+    }
+
+    delete newItem.source
+  } else if ('items' in newItem) {
+    // Pass topItem = false, since we don't want to use updatePlaylistFormat
+    // on these items.
+    newItem.items = await Promise.all(item.items.map(x => processSmartPlaylist(x, false)))
+  }
+
+  if ('filters' in newItem) filters: {
+    if (!isGroup(newItem)) {
+      console.warn('Filter on non-group (no effect):', newItem)
+      break filters
+    }
+
+    newItem.filters = newItem.filters.filter(filter => {
+      if ('tag' in filter === false) {
+        console.warn('Filter is missing "tag" property (skipping this filter):', filter)
+        return false
+      }
+
+      return true
+    })
+
+    Object.assign(newItem, filterTracks(newItem, track => {
+      for (const filter of newItem.filters) {
+        const { tag } = filter
+
+        let value = track
+        for (const key of tag.split('.')) {
+          if (key in Object(value)) {
+            value = value[key]
+          } else {
+            console.warn(`In tag "${tag}", key "${key}" not found.`)
+            console.warn('...value until now:', value)
+            console.warn('...track:', track)
+            console.warn('...filter:', filter)
+            return false
+          }
+        }
+
+        if ('gt' in filter && value <= filter.gt) return false
+        if ('lt' in filter && value >= filter.lt) return false
+        if ('gte' in filter && value < filter.gte) return false
+        if ('lte' in filter && value > filter.lte) return false
+        if ('least' in filter && value < filter.least) return false
+        if ('most' in filter && value > filter.most) return false
+        if ('min' in filter && value < filter.min) return false
+        if ('max' in filter && value > filter.max) return false
+
+        for (const prop of ['includes', 'contains']) {
+          if (prop in filter) {
+            if (Array.isArray(value) || typeof value === 'string') {
+              if (!value.includes(filter.includes)) return false
+            } else {
+              console.warn(
+                `Value of tag "${tag}" is not an array or string, so passing ` +
+                `"${prop}" does not make sense.`
+              )
+              console.warn('...value:', value)
+              console.warn('...track:', track)
+              console.warn('...filter:', filter)
+              return false
+            }
+          }
+        }
+
+        if (filter.regex) {
+          if (typeof value === 'string') {
+            let re
+            try {
+              re = new RegExp(filter.regex)
+            } catch (error) {
+              console.warn('Invalid regular expression:', re)
+              console.warn('...error message:', error.message)
+              console.warn('...filter:', filter)
+              return false
+            }
+            if (!re.test(value)) return false
+          } else {
+            console.warn(
+              `Value of tag "${tag}" is not a string, so passing "regex" ` +
+              'does not make sense.'
+            )
+            console.warn('...value:', value)
+            console.warn('...track:', track)
+            console.warn('...filter:', filter)
+            return false
+          }
+        }
+      }
+
+      return true
+    }))
+
+    delete newItem.filters
+  }
+
+  if (topItem) {
+    // We pass true so that the playlist-format-updater knows that this
+    // is going to be the source playlist, probably.
+    return updatePlaylistFormat(newItem, true)
+  } else {
+    return newItem
+  }
+}
+
+module.exports = processSmartPlaylist
diff --git a/todo.txt b/todo.txt
index f682a1a..044a508 100644
--- a/todo.txt
+++ b/todo.txt
@@ -23,3 +23,5 @@ TODO: Pressing enter in the queue seems to not be doing the right thing?
       It should NOT move the selected item anywhere in the queue; it should
       just select and play that track.
       (Done!)
+
+TODO: iTunes downloader - test this.